The Advantages of using High Quality Aggregates in Surface Course Pavements

Pavement performance is a function of its relative ability to serve traffic over a period of time. The aggregates used to make the surface course are directly related to the quality of the product.
When choosing a suitable aggregate, hard rock is often the only material that will produce a quality end product.
Many of the advantages of using hard rock to make surface course pavements include:
Safer Roads - It’s easy to provide safer roads with hard rock as your surface course aggregate. Hard rock has a high P.S.V. (Polished Stone Value) number which makes it possible to achieve a skid resistant road surface.
Economical Mix Designs – Surface course pavements are made up of aggregates and asphalt binders. Determining what aggregate to use, what asphalt binder to use and the optimum combination of these two ingredients is critical to achieve a quality end product.
Hard rock absorptions range is less than 1%; therefore a smaller amount of asphalt binder is required, resulting in a more economical product.
Plant Thruput - We have documented results gathered on West Indian paving projects over the years that demonstrate asphalt plant thruput comparing limestone or other soft rock with a dense granite rock. The results are as follows:

Increased plant thruput results in more production per shift and this means more asphalt laid in a day. Some projects have shown an increase from 400 to 700 tonnes per day or a 75% production increase.
Fuel Usage - Using a hard rock with low absorption will save one to two gallons of fuel per ton when drying the aggregates in the asphalt plant. With oil prices on the increase, the savings on fuel to dry the aggregates certainly must be considered.
Long Life Pavements - Using hard rock aggregates with superior engineering and mechanical properties will help achieve long life pavements. Various roadways and airport surfaces observed in the West Indies demonstrate that the making of asphalt from soft rock of lesser quality results in rapid deterioration of road surfaces, some of which need repaving in two or three years.